Various autoimmune diseases such as inflammatory bowel disease (IBD), rheumatoid arthritis, multiple sclerosis and psoriasis cause a decrease in QOL as a severe etiology cell and factor accompanying enhancement of a systemic new immune response. However, the existing therapeutic drugs show only limited effects, and therefore, the earliest possible development of a novel therapeutic drug has been desired.
Involvement of T cells, inter alia, Th17 cell and inflammatory cytokines (IL-17A, IL-17F and the like) produced thereby, in the pathology of these immune diseases has been drawing attention in recent years.
Moreover, it has been recently clarified that a Retinoid-related Orphan Receptor (ROR) γt, which is one of the orphan nuclear receptors, plays an important role in the differentiation of Th17 cells and production of IL-17A/IL-17F. That is, it has been reported that RORγt is mainly expressed in Th17 cells and functions as a transcription factor of IL-17A and IL-17F, as well as a master regulator of Th17 cell differentiation (non-patent documents 1 and 2).
Therefore, a medicament that inhibits the action of RORγt is expected to show a treatment effect on various immune diseases by suppressing differentiation and activation of Th17 cells.
As a compound that regulates RORγ activity, patent document 1 describes a compound represented by the formula:

wherein r5 and r6 may together form

As a compound having an RORα and RORγ inverse agonist activity, non-patent document 3 describes a compound represented by the formula:
(SR1001)and non-patent document 4 describes a compound represented by the formula:
(TO901317).
As a compound that antagonizes an RORγt activity, non-patent document 5 describes a compound represented by the formula:
(Digoxin).
As a compound having RORα and RORγ agonist activities, non-patent document 6 describes a compound represented by the formula:
(SR1078).
As a compound that regulates RORα and RORγ activities, non-patent document 7 describes a compound represented by the formula:
(Ursolic Acid).
As a compound that regulates RORα and RORγ activities, non-patent document 8 describes compounds represented by the formulas:
(7α-hydroxycholesterol)
(7β-hydroxycholesterol)
(24-ketocholesterol), and non-patent document 9 describes a compound represented by the formula:
(24S-hydroxycholesterol).
As a ligand of RORγ, non-patent document 10 describes compounds represented by the formulas:
